Add MIT license and package metadata

[rastagan-git]

Summary

• add the standard MIT License with copyright held by Tianyuan Chen
• declare the MIT SPDX license expression and include LICENSE in Python distributions
• clarify in the English and Chinese READMEs that third-party provider data remains governed by source-specific terms

Why

The public repository previously had no detectable software license, so default copyright restrictions applied and package artifacts did not declare a license.

Validation

• python -m pytest — 52 passed
• python -m ruff check . — passed
• python -m ruff format --check . — passed
• python -m build — source and wheel builds passed
• verified wheel metadata contains License-Expression: MIT and License-File: LICENSE
• verified the wheel includes aromanexus-0.3.0.dist-info/licenses/LICENSE